New organic disposable sensor will let diaper say baby needs changing

Researchers have unveiled a disposable organic sensor that can be embedded in a diaper and wirelessly let a carer know it needs changing.

The flexible integrated circuit printed on a single plastic film transmits information and receives its power wirelessly, and could potentially be manufactured for a few yen, the developers said.

The system, which uses organic materials that can be printed with ink-jet technology, was developed by a team led by professors Takayasu Sakurai and Takao Someya at the University of Tokyo.

In addition to use in infant diapers, the technology can be applied to adult diapers, a big-seller in rapidly aging Japan.

Regular diapers change color to indicate they are wet, but a care-giver still needs to take off the wearer’s clothes to see.

“If sensing is done electronically, you can tell simply by coming close to the wearer — without unclothing him or her,” Someya said.

The technology can also be placed directly on the skin like a plaster, in place of the often ring-shaped devices currently used in hospitals to monitor pulse and blood oxygen levels, he said.

Health care sensors often use silicon and other relatively rigid materials that can cause discomfort. The flexibility of a single sheet of plastic film reduces that discomfort and means it can be applied to a larger number of places, offering greater potential to monitor well-being.

The prototype is capable of monitoring wetness, pressure, temperature and other phenomena that cause a change in electrical resistance, said Someya, but the team would like to refine it to reduce power consumption before it goes into widespread use.

Currently, the data-reading device needs to be a few centimeters from the sensor, but Someya said the team is exploring whether they can boost the transmission distance.